Collapsible tubing



April 8', 1952 w. E. REJEsKl 2,592,335

COLLAPSIBLE TUBING Filed Feb. 24, 1949 2 SHEETS--SHEET l INVENToR v WILLIAM E'.REJESKI BY ms ATTORNEYS April 8, 1952 w. E. REJEsKl 2,592,335

COLLAPSIBLE TUBING Filed Feb. 24, 1949 2 SHEETS--SHEET 2 I w 29 Tige. mi- HJTTW MT m *7 INVENTOR WILLIAM E. REJESKI BY HIS ATTORNEYS Patented Apr. 8, 1952 COLLAPSIBLE TUBING William E. Rejeski, Hartford, Conn., assignor to The Wiremold Company, Hartford, Conn., a

corporation of Connecticut Application February 24, 1949 Serial No. 78,135

14 Claims.

, This invention relates to improvements in collapsible tubing. More particularly the invention relates to collapsible tubing formed of two elements such as a strip of fabric or other flexible material and a spiral of strip metal whose edges are folded over and interlock or interengage with the strip of flexible material.

In the process of collapsing tubing of this sort as heretofore made, the fabric or flexible strip would fold or be thrown inwardly. This inward encroachment upon the area enclosed by the tube reduced the volume of fiuid gas or air which the tube would pass because the free area for passage was reduced. Also the interior spiral caused by the inward fold of the fabric tended to create an interior surface in the tube which was less smooth and offered more surface resistance than desired for the ow of air or fluid through the tubing. These factors have proven commercially undesirable.

Therefore it is an object of the invention to provide an improved collapsible tubing construction in which the flexible strip element is thrown or folds outwardly as the tubing collapses or bends into curved shapes.

Another object of the invention is to provide tubing achieving the foregoing objective which will at the same time require less metal in the metal spiral element of the tubing.

Another object is to provide means on the metal element to more securely hold the edges of the flexible element.

Other objects and advantages of the invention will become apparent as the invention is den scribed in connection with the accompanying drawings.

In the drawings:

Fig. 1 is a fragmentary sectional view of a portion of tubing in the process of formation embodying the principles of this invention;

Fig. 2 is a fragmentary longitudinal sectional view of two convolutions of collapsible tubing embodying the invention;

Fig. 3 is a view similar to Fig. 2 but with the tubing collapsed;

Fig. l is an elevation view of expanded collapsible tubing embodying the invention;

Fig. 5 is a view similar to Fig. 4 but with the tubing collapsed;

Fig. 6 is a fragmentary sectional view of one convolution of flexible tubing embodying an alternate form of the invention;

Fig.v'7 is a fragmentary sectionall view of a convolution of collapsible tubing embodying another alternate form of the invention;

Fig. 8 is a fragmentary sectional view of a portion of a convolution similar to the form of Figs. 1-3 but with the advance edge of the fabric not folded double;

Fig. 9 is a fragmentary plan view of the metal strip element of the tubing;

Fig. 10 is a longitudinal section view of the metal strip element of the tubing taken along line Ill-I0 of Fig. 9.

Referring to the drawings, the tubing shown in Figs. 1-3 comprises a metallic spiral I0 formed of thin strip metal having its edges folded or reversely bent outwardly. The forward edge I2 (i. e.. the right edge in Figs. 1-3) is folded more shortly, or in other words, farther from the center line of the strip than the trailing edge I4 (i. e., the left edge in Figs. 1-3).

The flexible element of the tube may be a strip 20 of treated or untreated fabric or any other flexible material suited to the requirements of usage. One edge 22 of the flexible strip 20 is inserted under the longer folded edge portion I4 during the formation of the tubing and prior of the metal spiral is bent down tight upon boththe edge portions 22 and 26 of the flexible strip to firmly grip them and frictionally hold them. The shorter folded edge I2 of the metal spiral l0 tends to lock the flexible strip in place. To

accomplish that objective the spacing between the extremities of the folded edges I2 and I4.

is made small. Hence, should the edges of the flexible strip tend to pull out from under the edge I4 of the metal spiral, the flexible strip would tend to jam between and be held by the edges I2 and I4.

When constructed in the foregoing manner the flexible or fabric portion' of the tubing, when thertubing collapses, will move outwardly and fold as indicated at 28 in Figs. 3 and 5 thus presenting a relatively smooth interior surface within the tubing.

To insure the outward folding, the folded portion is pinched during the formation of the tubing, the pinching being done while the metalV convolutions of the' tube are close together.,`

While these convolutions are together there is an excess of fabric which folds over as at 28y 5). In collapsing the tube from the position of` Fig. 4fthe part 21 of the fabric which follows the pinch 28 (i. e. at its left) moves over ythe part 29 of the fabric which isV in advance V. H f.

the pinch (i. e. at its right). In other words, both parts 2l and 29 move to the right but part 2I turns upside down and moves over the part 29; and part 29 moves towards the next convolution.

In Fig. 6 an alternate form is shown wherein the edges of the fabric or flexible element are folded and tucked under the longer edge I'I4, as in the previously-described form. However, the leg I I4 is longer than the edge I4 in the previous form and when bent down it overlaps the shorter edge II2 which is or may be about the same as the edge I2.

In Fig. 7 a third form is illustrated wherein the longer edge 2I4 may be of the same extent as I4 in Figs. l-3; or it may be longer as in Fig. 6. But the longer edge 2I4 is bent down as in Figs. 1-3 to frictionally hold and firmly grip the edges of the fabric or flexible material between it and the body ZID of the metal spiral.

In Fig. 7 the short edge 2I2 is bent over on top of the longer edge with the layers of ilexible material between the shorter and the longer edges. In this form the pull of the ilexible material is always indirect or, in other words, around an edge of the spiral, thus tending further to inhibit or prevent pulling out of the fabric edges from the metal spiral.

It is not essential to double over the forward edge (as at 26, Figs. 1 3, 6 and 7) when inserting that edge under the flange I4. Insertion of a single thickness will suflice, as illustrated at 25 in Fig. 8.

In some cases it may be advisable to provide means to more securely hold the fabric edges under the flange I4. For that purpose I provide a series of serrations 30 in the edge of the flange I4. Each serration is made by cutting diagonally inwardly from the edge in backward direction and then bending down the back side 3'I of the cut to form a sharp-edged tooth 32 which is obliquely inclined inwardly of the tube. These teeth bite into the flexible material or fabric under the flange I4 and thus securely hold the material. rated metal edge a crack will occur in the flange at every other notch, running to the joint of the flange and the body of the strip. These cracks relieve thetension in the flange of the strip.

In all forms of the invention the collapsing of. the tubing is facilitated by both edges of the ilexible material lying in the same direction. Furthermore, because the exible material moves outwardly upon collapse of the tubing, the tubing may be collapsed to a shorter length than in the prior collapsible tubing wherein the flexible material could move inwardly and thus occupy some of the space between the convolutions of the metallic spiral.

The tubing described herein can be made rapidly by the machine and process claimed in my copending application Serial No. 80,675, filed March 10, 1949, and issued concurrently herewith.

Many modifications of the invention will occur to those skilled in the art and therefore I do not limit the invention to the embodiments shown.

What is claimed is:

l. Collapsible tubing comprising a strip of metal wound into a spiral, an edge of said spiral being folded over outwardly, a strip of flexible material having one edge inserted under said folded edge of one convolution of said spiral, the

Often in bending the serj,

other edge of said flexible strip being inserted under the same edge of the adjacent convolution of said spiral, said folded spiral edge being bent down to frictionally hold the edges of the flexible strip.

2. Collapsible tubing as claimed in claim 1 wherein both edges of the spiral are folded over outwardly.

3. Collapsible tubing as claimed in claim 2 wherein the folded edge of the spiral under which the ilexible strip is held extends toward and close to and cooperates with the other edge tending to lock the edges of the ilexible strip in place.

4. Collapsible tubing as claimed in claim 1 wherein one of the edges of the flexible strip is doubled over upon itself beneath said folded edge of the metallic spiral.

5. Collapsible tubing as claimed in claim 4 wherein both edges of the metallic spiral are folded outwardly.

'6. Collapsible tubing as claimed in claim 5 wherein the folded edge of the spiral under which the flexible strip is held extends toward and cooperates with the other edge tending to lock the edges of the flexible strip in place.

7. Collapsible tubing as claimed in claim l wherein both edges of the metallic spiral are folded outwardly and the edge under which the flexible strip is inserted partially overlies the other edge of the spiral and is bent down thereon so as to hold the flexible strip between said other edge and itself.

8. Collapsible tubing as claimed in claim 7 wherein one of the edges 0f the flexible strip is doubled over on itself beneath the' edge of the l,

metallic spiral.

9. Collapsible tubing as claimed in claim l wherein the other edge of the metallic spiral is also folded over outwardly and overlies the edge of the spiral under which the ilexible strip is held, thereby to hold the flexible strip between said two foldedover edges 0f the spiral.

10. Collapsible tubing as claimed in claim 9 wherein one of the edges of the flexible strip is doubled over on itself beneath the edge of the metallic spiral.

ll. Collapsible tubing as claimed in claim 1 having means formed on the edge of spiral biting into the flexible strip.

l2. Collapsible tubing as claimed in claim 1 having diagonal cuts in the edge of the spiral adjacent to which teeth are bent down into engagement with the flexible strip at spaced points along said edge of thespiral.

13. Collapsible tubing as claimed in claim 1 wherein the flexible strip is pinched to form an outwardly-extending ridge which causes the ilexible strip material to fold outside the convolutions of the metal strip when the tubing.

collapses.

14. Collapsible tubing as claimed in claim 13 having means formed on the edge of the spiral biting into the flexible strip.

WILLIAM E. REJESKI.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 2,337,374 Chernack Dec. 2l, 1943 2,340,794 Chernack Feb. 1, 194.4 

